This invention relates to a device for illuminating and observing various surfaces of a workpiece that are to be subjected to autofocus and video inspection apparatus for accurate measurement of such surfaces. More particularly, this invention relates to a novel multi-directional mirror device and method for effecting inspection and autofocus measurement of selected surfaces of a workpiece.
There are currently available in the marketplace apparatus of various designs for illuminating and effecting accurate measurement of various surfaces of a manufactured workpiece. Typical such apparatus includes a precision optical inspection system for directing illumination downwardly onto an inspected object placed on a horizontal transparent stage. The imaging optics of such apparatus, for example the objective lens or its housing, can be moved vertically to achieve focus, while the stage or work support can be shifted laterally in intersecting X and Y directions to permit observation of different surfaces of the work being inspected. A substage illuminator can be employed beneath the transparent stage to project a silhouette or shadow of the object's features for inspecting still other surface features of the work. The U.S. Pat. Nos. 5,832,107, 5,668,665, and U.S. Pat. No. 5,389,774 disclose various such systems for directing illumination downwardly through an objective lens or lens housing onto a workpiece for purposes of inspecting and effecting measurements of various surfaces thereof. Still other illuminating apparatus, such as disclosed for example in U.S. Pat. No. 6,179,439 have been employed with such inspection apparatus in order to direct illumination laterally onto side surfaces of the workpiece that is being inspected.
However, in order to view an object from different directions by inspection apparatus of the type noted above, it is necessary for the inspected object to be manipulated so as to present alternative views to the inspection lens system. Typically this manipulation can be accomplished manually or by using grippers and rotary axes to reorient the position of the object. To avoid the necessity of manipulating the object, it is conceivable that a more complex system might incorporate multiple optical systems for viewing an object from different directions simultaneously. Also while it has been proposed to employ an adjustable or a swiveling observation tube or lens as disclosed for example in U.S. Pat. No. 6,172,804, such devices can be expensive to manufacture and to incorporate into inspection apparatus of the type described. To avoid such problems, some optical systems which are designed with sufficient working distance—i.e., clearance between the optics and the inspected object, have sometimes employed mirrors to provide views of the object's sides from above. However, such mirrors are typically secured or held upon the XY supporting stage, and are not capable of viewing inside surfaces such as the internal walls of an open box or an inner surface of a cylinder.
It is an object of this invention, therefore, to provide for autofocus measurement equipment a novel multi-directional mirror device which is releasably attached to and adjustable relative to the inspecting optics selectively to direct a variety of different images to the system optics.
A more specific object of this invention is to provide any one of a number of different, replaceable mirrors each of which is disposed to be releasably mounted on and suspended beneath the objective lens housing of inspection apparatus to be disposed in a plane inclined to and extending transversely of the optical axis of the apparatus, thereby to project the imaging optical axis at some angle to the vertical, and for rotation selectively into different angular of positions about the optical axis.
It is an object also of this invention to provide a novel method of inspecting and effecting autofocus measurements of various surfaces of a workpiece along intersecting optical axes.
Still other objects of this invention will be apparent hereinafter from the specification and from the recital of the appended claims, particularly when read in conjunction with the accompanying drawings.